Fungicidal compositions

ABSTRACT

An improved fungicidal composition is a mixture of (a) fungicide used to combat phytopathogenic fungi and (b) at least one phosphonate or phosphinate of formula R 1  R 2  P(O)OR 3  where R 1  is C 6-20  alkyl, C 6-20  alkoxy or optionally substituted phenyl, R 2  is benzyl, C 6-20  alkyl optionally interrupted by NH or O, di-C 6-20  alkylamino or the group --CH 2  CH 2  --R 1  P(O)OR 3 , and R 3  C 6-20  alkyl. Some of the compounds of formula (I) are novel.

This application is a 371 of PCT/GB97/01738, filed Jun. 26, 1997.

FIELD OF THE INVENTION

This invention relates to new fungicidal compositions.

PRIOR ART

U.S. Pat. No. 2,927,014 discloses phosphonates and phosphinates having herbicidal activity. In WO 9418837 and WO 9304585, it is disclosed that certain phosphonates can enhance the activity of specified herbicides. We have now found that such compounds can also be used with advantage in association with certain fungicides used to combat phytopathogenic fungi.

DESCRIPTION

The invention provides a fungicidal composition which comprises a mixture of

(a) fluquinconazole or azoxystrobin, and

(b) at least one phosphonate or phosphinate of formula I ##STR1## where

R¹ is C₆₋₂₀ -alkyl, C₆₋₂₀ -alkoxy or optionally substituted phenyl

R² is benzyl, C₆₋₂₀ -alkyl, optionally interrupted by NH or O, di-C₆₋₂₀ -alkylamino or the group ##STR2## and

R³ is C₆₋₂₀ -alkyl.

Phosphonates of formula I wherein R¹ is C₆ -C₂₀ -alkoxy and R² is C₆ -C₂₀ -alkyl are known. They are made for example according the disclosure in DE 1,963,014.

Phosphinates of formula I wherein R¹ is C₆ -C₂₀ -alkyl and R² is phenyl can be prepared by catalytically induced addition of olefins to phenyl monoalkylphosphonites which are preferably prepared as described in DE patent 196 041 95.

Ethane-1,2-diphosphonic acid tetraalkyl esters of formula I wherein R¹ is C₆ -C₂₀ -alkoxy and R² is the group ##STR3## can be made by addition of the appropriate phosphonates to a dialkyl vinylphosphonate in the presence of basic catalysts such as sodium methylate or sodium hydride.

Alkyl- or dialkylaminoalkylphosphonic acid dialkyl esters of the formula ##STR4## wherein R³ is as defined above and R⁵ is R³ or hydrogen and x is 0 or 1 can be prepared according to two different methods. Compounds wherein x is 0 are made according to the following equation ##STR5## Compounds wherein x is 1 and made according to the following equation: ##STR6##

The addition of the amine is made in the presence of basic catalysts such as sodium methylate of sodium hydride according to the process described by A. N. Pudovik et al., Doklady Akad. S.S.S.R. 80365(1951); (A 50, 4143(1956).

Azoxystrobin is the common name for the fungicide methyl (E)-2-{2-[6-(2-cyanophenoxy)pyrimidin-4-yloxy]phenyl}-3-methoxyacrylate and fluquinconazole is the common name for the fungicide 3-(2,4-dichlorophenyl)-2-(1H-1,2,4-triazol-1-yl)-4(3H)-quinazolinone).

We have found that phosphonates of formula I, which have little or no activity in their own right considerably enhance the fungicidal activity of fluquinconazole and azoxystrobin.

The weight ratio of component a) to b) is generally between 10:1 and 1:10, preferably between 3:1 and 1:5.

The compound of formula I can be added to conventional formulations of component a). It may be desirable to also add small quantities of solvent and/or surfactant especially a non-ionic surfactant, and other additives such as fatty acids to improve the emulsifiability of the compound of formula I.

The following Examples illustrate the invention. Examples 1 to 6 describe the preparation of what are believed to be novel phosphonates and phosphinates, which can be used in admixture with azoxystrobin or fluquinconazole.

EXAMPLE 1

Into a reaction vessel, which was heated to 100° C., with a reflux condenser (-15° C.), were simultaneously added aqueous formaldehyde (12.17 g of 37% solution) and a mixture of di(2-ethylhexyl)amine (36.22 g) and di(2-ethylhexyl) phosphonate (45.96 g). The mixture was heated for 1 hour with stirring and then cooled to 20° C. The water was removed by distillation under reduced pressure to give di(2-ethylhexyl){[di(2-ethylhexyl)amino]methyl}phosphonate, as a colourless liquid (n_(D) ²⁰ =1.4563).

EXAMPLE 2

A mixture of 2-ethylhexyl vinylphosphonate, 2-ethylhexylamine (66.50 g) and sodium hydride (0.10 g) was stirred at 130° C. for 6 hours. After addition of an additional amount of sodium hydride (0.10 g) and stirring 9 hours there was obtained di(2-ethylhexyl){[2-ethylhexyl)amino]methyl}phosphonate, as a colourless liquid (n_(D) ²⁰ =1.4537).

EXAMPLE 3

To a mixture of 2-ethylhexyl vinylphosphonate (49.9 g), di(2-ethylhexyl) phosphonate (45.9 g) and THF (80 ml) was added to 20° C. with stirring, a solution of sodium methylate in methanol until the mixture reached pH 8-9. The mixture was stirred for 12 hours and water (100 ml) and ethyl acetate (200 ml) added. The organic phase was separated, dried with sodium sulfate, filtered and the solvent evaporated under reduced pressure to give tetra(2-ethylhexyl) ethane-1,2-diphosphonate as a colourless liquid, n_(D) ²⁰ =1.4488.

EXAMPLE 4

A mixture of 2-ethylhexyl vinylphosphonate (49.90 g), octadecylamine (40.43 g) and sodium hydride 0.10 g was stirred at 140° C. for 6 hours. Water (100 ml) and ethyl acetate (200 ml) were added. The organic phase was separated, dried with sodium sulfate, filtered and the solvent evaporated under reduced pressure to give di(2-ethylhexyl)[2-(octadecylamino)ethyl]phosphonate, as colourless liquid n_(D) ⁴⁰ =1.4541.

EXAMPLE 5

A mixture of tetradec-1-ene (30.05 g) and benzoyl peroxide (0.3 g) was added dropwise with stirring to 2-ethylhexyl phenylphosphonate (38.95 g) at 160° C. The resulting mixture was stirred for 6 hours to give 2-ethylhexyl phenyl tetradecylphosphinate, as a colourless liquid n_(D) ²⁰ =1.4813.

EXAMPLE 6

In a similar manner to example 5, starting from octadec-1-ene, there was obtained 2-ethylhexyl phenyl octadecylphosphinate, as colourless liquid n_(D) ²⁰ =1.4729.

EXAMPLE 7

Wheat plants were inoculated with Erysiphe graminis (powdery mildew). One day after inoculation, they were sprayed with fluquinconazole, obtained by diluting with water to the desired concentration, a suspension concentrate comprising 50% by weight active ingredient, at a rate of 50 g fluquinconazole/ha either alone or mixed with various inactive phosphonate or phosphinate esters added at a concentration of 0.1% v/v, together with an appropriate emulsifier.

One week after spraying, the wheat was assessed for control of disease. The results are as follows:

    ______________________________________                                         Phosphonate/phosphinate added                                                                              % control                                          ______________________________________                                         dihexyl octylphosphonate    97.2                                                 dioctyl octylphosphonate 100                                                   di(2-ethylhexyl) hexylphosphonate 100                                          di(2-ethylhexyl) octylphosphonate 100                                          di(2-ethylhexyl) decylphosphonate 100                                          di(2-ethylhexyl) dodecylphosphonate 100                                        di(2-ethylhexyl) tetradecylphosphonate 100                                     2-ethylhexyl phenyl tetradecylphosphinate (Example 5) 100                      tetra(2-ethylhexyl) ethane-1,2-diphosphonate (Example 3) 100                   2-ethylhexyl phenyl octadecylphosphinate (Example 6) 100                       di(2-ethylhexyl) {[di(2-ethylhexyl)amino]methyl}phosphonate 85.2                                          (Example 1)                                         di(2-ethylhexyl) [2-(octadecylamino)ethyl]-phosphonate 93.5                    (Example 4)                                                                    nil 0                                                                        ______________________________________                                    

EXAMPLE 8

In a similar manner, Example 7 was repeated with some of the phosphonates and with replacing fluquinconazole with azoxystrobin. The results are as follows

    ______________________________________                                                                                 con-                                     active Rate  Rate trol                                                         ingredient (g/ha) Phosphonate (% v/v) (%)                                    ______________________________________                                         azoxystrobin                                                                           62.5   --                 --    29                                       azoxystrobin 125 -- -- 30                                                      azoxystrobin 250 -- -- 94                                                      azoxystrobin 62.5 di(2-ethylhexyl) octylphosphonate 0.2 98                     azoxystrobin 125 di(2-ethylhexyl) octylphosphonate 0.2 100                     azoxystrobin 250 di(2-ethylhexyl) octylphosphonate 0.2 100                     azoxystrobin 62.5 compound of Example 4 0.2 100                                azoxystrobin 125 compound of Example 4 0.2 100                                 azoxystrobin 250 compound of Example 4 0.2 100                               ______________________________________                                    

EXAMPLE 9

Example 7 was repeated in test against Puccinia recondita using azoxystrobin

Results are as follows:

    ______________________________________                                                                                 con-                                     active Rate  Rate trol                                                         ingredient (g/ha) Phosphonate (% v/v) (%)                                    ______________________________________                                         azoxystrobin                                                                           1      --                 --    8                                        azoxystrobin 5 -- -- 9                                                         azoxystrobin 20 -- -- 23                                                       azoxystrobin 1 di(2-ethylhexyl) octylphosphonate 0.2 29                        azoxystrobin 5 di(2-ethylhexyl) octylphosphonate 0.2 85                        azoxystrobin 20 di(2-ethylhexyl) octylphosphonate 0.2 91                       azoxystrobin 1 compound of Example 4 0.2 79                                    azoxystrobin 5 compound of Example 4 0.2 90                                    azoxystrobin 20 compound of Example 4 0.2 93                                 ______________________________________                                    

EXAMPLE 10

The following are typical formulations incorporating fluquinconazole and the preferred phosphonate according to the invention.

a) an SC formulation was made from the following components

    ______________________________________                                         Ingredient           g/l                                                       ______________________________________                                         fluquinconazole      100                                                         di(2-ethylhexyl) octylphosphonate 320                                          emulsifiers 190                                                                buffer 10                                                                      structuring agent 30                                                           vegetable oil to volume 327                                                  ______________________________________                                    

b) a suspoemulsion was made to the following composition.

    ______________________________________                                         Ingredient           g/l                                                       ______________________________________                                         fluquinconazole      54                                                          prochloraz 174                                                                 dispersant 25                                                                  emulsifiers 180                                                                buffer 10                                                                      crystal growth inhibitor 38                                                    di(2-ethylhexyl) octylphosphonate 174                                          aromatic hydrocarbon solvent 192                                               propylene glycol 40                                                            antifoam 2                                                                     biocide 2                                                                      structuring agent 7.5                                                          water to volume 176                                                          ______________________________________                                     

What is claimed is:
 1. A fungicidal composition which comprises a mixture of(a) a fungicidally effective amount of fluquinconazole or azoxystrobin and (b) an enhancing effective amount of at least one phosphonate or phosphinate of formula I ##STR7## where R¹ is C₆₋₂₀ -alkyl, C₆₋₂₀ -alkoxy or optionally substituted phenyl R² is benzyl, C₆₋₂₀ -alkyl, optionally interrupted by NH or O, di-C₆₋₂₀ -alkylamino or the group ##STR8## and R³ is C₆₋₂₀ -alkyl.
 2. A fungicidal composition according to claim 1, wherein R¹ is C₆₋₂₀ alkyl, and R² is C₆₋₂₀ alkyl optionally interrupted by NH.
 3. A fungicidal composition according to claim 2, containing one or two 2-ethylhexyl groups.
 4. A fungicidal composition according to claim 3, wherein (b) is di(2-ethylhexyl)octyl phosphonate.
 5. A fungicidal composition according to claim 4, wherein (a) is azoxystrobin.
 6. A fungicidal composition according to claim 5, wherein the ratio of (a) to (b) is between 1:10 and 10:1 by weight.
 7. A fungicidal composition according to claim 6, wherein the ratio of (a) to (b) is between 3:1 and 1:5.
 8. A fungicidal composition according to claim 3, wherein (b) is di(2-ethylhexyl)[2-(octadecylamino)ethyl]phosphonate.
 9. A fungicidal composition according to claim 3, wherein (a) is fluquinconazole.
 10. A fungicidal composition according to claim 1, wherein (a) is fluquinconazole.
 11. A fungicidal composition according to claim 1, wherein (a) is azoxystrobin.
 12. A fungicidal composition according to claim 1, wherein the ratio of (a) to (b) is between 1:10 and 10:1 by weight.
 13. A fungicidal composition according to claim 1, wherein the ratio of (a) to (b) is between 3:1 and 1:5 by weight.
 14. A method of augmenting the activity of the fungicides fluquinconazole or azoxystrobin used to combat phytopathogenic fungi which comprises employing a fungicidally effective amount of said fungicides in combination with an enhancing effective amount of at least one phosphonate or phosphinate of the formula R¹ R² P(O)OR³ where R¹ is C₆₋₂₀ alkyl, C₆₋₂₀ alkoxy or optionally substituted phenyl, R² is benzyl, C₆₋₂₀ alkyl, optionally interrupted by NH or O, di-C₆₋₂₀ alkylamino or the group --CH₂ CH₂ --R¹ P(O)OR³, and R³ is C₆₋₂₀ alkyl.
 15. The method of claim 14, wherein R¹ is C₆₋₂₀ alkyl, and R² is C₆₋₂₀ alkyl optionally interrupted by NH.
 16. The method of claim 15, wherein the phosphonate or phosphinate contains one or two 2-ethylhexyl groups.
 17. The method of claim 16, wherein the fungicide is azoxystrobin and is agumented by di(2-ethylhexyl)octyl phosphonate.
 18. The method of claim 14, wherein the ratio of the fungicide to said at least one phosphonate or phosphinate is between 1:1 and 1:10 by weight.
 19. The method of claim 14, wherein the ratio of the fungicide to said at least one phosphonate or phosphinate is between 3:1 and 1:5 by weight. 